Cardiovascular Effects of Propranolol during Acute Experimental Anemia in Dogs

Abstract

The effects of beta blockade on the cardiovascular responses observed 30 and 60 min following the production of anemia were investigated in anesthetized dogs. Comparisons were made between two groups of anemic animals, one of which was given propranolol prior to the production of anemia by rapid dextran-for-blood exchange. Pretreatment of anemic animals with propranolol did not affect the change in cardiac output [Formula: see text], stroke volume (V_S), arterial oxygen transport [Formula: see text] or right ventricular end diastolic pressure P_RVED 30 min following the exchange procedure. However, by 60 min the propranolol-treated group had a lower [Formula: see text] and [Formula: see text] and a higher P_RVED than the untreated group. The similariiies between the two anemic groups at 30 min postexchange indicated that neither sympathetic beta blockade nor the direct myocardial depressant effects of propranolol abrogate the cardiac response to anemia at this time. The increase in P_RVED in the propranolol-treated anemic series, 60 min postexchange, coupled with the failure of [Formula: see text] to increase between 30 and 60 min, as observed in the untreated anemic series, may suggest that the treated group was exhibiting early signs of reduced cardiac contractility.